The invention relates to a radial-axial roller bearing, having an inner ring, coaxially with which an outer ring is disposed, between which rolling bodies roll in order to absorb radial forces, and having cylindrical rolling bodies disposed in cages on both sides to absorb lateral forces, the tracks of which are formed on one side by the end faces of the outer ring and on the other side by a runner plate in each case.
Such a generically combined radial-axial roller bearing is shown on page 136 of the INA catalog Wxc3xa4lzlager 305. It consists of an inner ring, an outer ring disposed coaxially therewith and cylinder rollers rolling between them on associated tracks. The end faces of the outer ring simultaneously form tracks for axial bearings disposed on the right and left, whose other track is formed by a runner plate in each case. The inner ring of the radial bearing is integrally connected to a runner plate of an axial bearing, in other words this part, composed of inner ring and runner plate, is of L-shaped form. The separating plane between this L-shaped component and the other running plate is positioned so that it is placed outside the radial bearing. It lies in the extended radial plane of the running surface of an axial bearing.
A disadvantage of this arrangement is that such a combined bearing arrangement, because of the one runner plate that is not connected to the inner ring, is relatively soft, in other words not tilt-resistant, especially under high stresses. A further disadvantage can be seen in the fact that, because of the differently shaped bearing components, their production is relatively elaborate and hence costly.
It is therefore an object of the present invention to develop a generic radial-axial roller bearing unit which can be produced cost-effectively and which also possesses high tilt resistance.
This object is achieved, according to the invention, and in accordance with the characterizing clause of claim 1, in that the inner ring is formed from two part-rings which are integrally connected to the runner plates, a separating plane being placed between the part-rings in the track region of the roller bearing.
The advantage of the solution according to the invention lies, in particular, in its increased tilt resistance under high axial forces, the two L-shaped part-rings being centered relative to one another in the track region of the radial bearing by its rolling bodies as a result of the position of their separating plane. This means that, as a result of the contact between the rolling bodies, formed as cylinder rollers, of the radial bearing and the two L-shaped part-rings, a radial offset between the two is precluded.
Thus it is envisaged, that the separating plane is placed in the center of the track region of the radial bearing. This central position permits the two part-rings to be produced as mirror images, and it is also sufficient for the centering of the two part-rings if the separating plane between the two is placed not necessarily at the center of the rolling bodies of the radial bearing but outside it.
It is envisaged that the inner ring is initially machined as a one-piece component and is split into the two part-rings after its production. This manner of production is particularly advantageous, since otherwise different tolerances arise in the tracks and bores if the inner ring is machined as an individual part-ring.
In accordance with another feature of the invention, that the part-rings are retained one upon the other by fixing screws, the number of fixing screws depending on the axially acting forces.
In accordance with an additional feature of the invention it is envisaged that the cylindrical rolling bodies of the axial bearings are each guided by a rim which is disposed either on the outer ring or on the runner plates. The advantage of this alternative solution lies in the fact that the rim now takes over the guidance of the rolling bodies of the axial bearing. In this manner, slip components of the friction are reduced, because better guidance is provided by the rim, in other words the friction of the cylinder rollers on the cage webs is eliminated.
In this case, it may be expedient if the cage is formed not as a whole but, from individual segments abutting one another in the peripheral direction and each receiving a cylindrical rolling body. Advantageously, the segments each have in at least one part-region of their radial extent an arculate line of delimitation lying opposite one another in the peripheral direction in a manner such that a contact point is formed between two neighboring segments and is disposed in the region between the part-circular line and the rim. In this manner, the minimum possible friction between the neighboring segments is achieved. It is also possible for a spring means to be disposed between neighboring segments. Finally, the segments each comprise, on their radially inward sides, two protuberances which are mutually spaced in the peripheral direction. As a result of the contact between these protuberances and the inner ring, rough alignment of the axial bearing is achieved, the fine adjustment thereof being provided by the contact between the rolling bodies and the rim.
The invention will be explained in detail with reference to the examples of embodiment that follow.